Effect of Radiotherapy After Mastectomy and Axillary Surgery on 10-Year Recurrence and 20-Year Breast Cancer Mortality

Research · March 19, 2014

   

TAKE-HOME MESSAGE

• Radiotherapy did not significantly affect locoregional recurrence, overall recurrence, or breast cancer mortality in women with axillary dissection and no positive nodes. In women with axillary dissection and more than one node, radiotherapy significantly reduced locoregional recurrence, overall recurrence, and breast cancer mortality. Systemic therapy in patients with axillary dissection and one to three nodes further reduced locoregional recurrence, overall recurrence, and breast cancer mortality. 

• Advances in diagnosis and treatment of breast cancer have reduced the risk of recurrence and mortality, and advances in radiotherapy techniques have improved over the course of follow-up for many of the women in these trials (in some cases, >20 years). Therefore, the authors concluded that today the absolute gains from radiotherapy following mastectomy may be smaller than those in this analysis, although, proportionately, the benefits may well be larger for many women with a lower risk for recurrence.

ABSTRACT

BACKGROUND

Postmastectomy radiotherapy was shown in previous meta-analyses to reduce the risks of both recurrence and breast cancer mortality in all women with node-positive disease considered together. However, the benefit in women with only one to three positive lymph nodes is uncertain. We aimed to assess the effect of radiotherapy in these women after mastectomy and axillary dissection.

METHODS

We did a meta-analysis of individual data for 8135 women randomly assigned to treatment groups during 1964–86 in 22 trials of radiotherapy to the chest wall and regional lymph nodes after mastectomy and axillary surgery versus the same surgery but no radiotherapy. Follow-up lasted 10 years for recurrence and to Jan 1, 2009, for mortality. Analyses were stratified by trial, individual follow-up year, age at entry, and pathological nodal status.

FINDINGS

3786 women had axillary dissection to at least level II and had zero, one to three, or four or more positive nodes. All were in trials in which radiotherapy included the chest wall, supraclavicular or axillary fossa (or both), and internal mammary chain. For 700 women with axillary dissection and no positive nodes, radiotherapy had no significant effect on locoregional recurrence (two-sided significance level [2p]>0·1), overall recurrence (rate ratio [RR], irradiated vs not, 1·06, 95% CI 0·76–1·48, 2p>0·1), or breast cancer mortality (RR 1·18, 95% CI 0·89–1·55, 2p>0·1). For 1314 women with axillary dissection and one to three positive nodes, radiotherapy reduced locoregional recurrence (2p<0 0="" 1133="" 1314="" 1772="" 2p="0·04).</p" 95="" again="" and="" axillary="" both="" breast="" cancer="" ci="" cyclophosphamide="" dissection="" fluorouracil="" for="" four="" given="" groups="" in="" locoregional="" methotrexate="" more="" mortality="" nodes="" of="" or="" overall="" p="" positive="" radiotherapy="" recurrence="" reduced="" systemic="" tamoxifen="" them="" therapy="" these="" trial="" trials="" was="" were="" which="" with="" women="">

INTERPRETATION

After mastectomy and axillary dissection, radiotherapy reduced both recurrence and breast cancer mortality in the women with one to three positive lymph nodes in these trials even when systemic therapy was given. For today's women, who in many countries are at lower risk of recurrence, absolute gains might be smaller but proportional gains might be larger because of more effective radiotherapy.

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The Lancet

Effect of Radiotherapy After Mastectomy and Axillary Surgery on 10-Year Recurrence and 20-Year Breast Cancer Mortality: Meta-Analysis of Individual Patient Data for 8135 Women in 22 Randomised Trials

Lancet 2014 Mar 19;[EPub Ahead of Print], P McGale, C Taylor, C Correa, D Cutter, F Duane, M Ewertz, R Gray, G Mannu, R Peto, T Whelan, Y Wang, Z Wang, S Darby